s.surf.tps

[Martin Ameskamp]

> Martin are you using the new or old s.surf.tps? 
	
	The new one by now (s.surf.2d from /grass/incoming/interp_lib_new.shar)

> raster files with all zeroes can occur if your data are floats
> 0-1 and integers make them all zeroes. It is possible that your
> new data set needs completely different parameters than what
> you were using before and that's why you are getting the visible segments.
> (for visible segments increase npmin - with old s.surf.tps you
> can go up to about 350, with new one, I have used npmin for some
> very bad data as large as 600 with good results).

	Well, I'm still at the same point - nothing but zeroes.
	My site file looks like this:

	619946.25|4176606.87|#58000
	619943.75|4176615.62|#58000
	619929.37|4176638.12|#58000
	619904.37|4176671.87|#58000
	619893.75|4176681.87|#58000
	619893.75|4176709.37|#58000
	619893.75|4176771.87|#58000

	(that's file sh2, heights in cm)
	The region is as follows:
	north:      4179364.07936508
	south:      4176563.19047619
	east:       621668.20404722
	west:       619370.06576728
	nsres:      20.00634921
	ewres:      19.98381113
	rows:       140
	cols:       115


	and the history of the elevation file looks like this:
	Thu Aug 11 17:28:05 1994
	e2
	PERMANENT
	ma
	raster
	site file sh2

	generated by s.surf.2d
	tension=40.000000, smoothing=0.100000
	dnorm=15705.616146, dmin=9.991906, zmult=0.010000
	segmax=40, npmin=200, errtotal=0.000000
	zmin_data=0.000000, zmax_data=0.000000
	zmin_int=0.000000, zmax_int=0.000000

	You'll notice that zmin_data and zmax_data are zero.

	I've run the same thing through the old s.surf.tps. That gives me a 
	file without obvious segmentation, but with weird values (not a lot of
	connection to the site values). The history of this file is:
	(I've changed the resolution to 50m from 20m above)

	Thu Aug 11 17:55:33 1994
	e3
	PERMANENT
	ma
	raster
	site file sh2

	generated by s.surf.tps
	tension=40.000000, smoothing=0.000000
	dnorm=1002.899713, dmin=24.979764, zmult=0.010000
	segmax=40, npmin=150, errtotal=0.000000
	zmin_data=0.000000, zmax_data=860.000000
	zmin_int=-3532.220660, zmax_int=6055.869155

	Increasing the tension to 80 yields:

	Thu Aug 11 18:27:18 1994
	e4
	PERMANENT
	ma
	raster
	site file sh2

	generated by s.surf.tps
	tension=80.000000, smoothing=0.000000
	dnorm=1002.899713, dmin=24.979764, zmult=0.010000
	segmax=40, npmin=150, errtotal=0.000000
	zmin_data=0.000000, zmax_data=860.000000
	zmin_int=-763.460313, zmax_int=1086.388382

	The actual values in the site file range from 52000 to 92000.
	I guess the high values are cut of by dmin, but there's definitely
	no value lower than 52000 (or 520 with zmult) in the site file.
	(sh2 contains 4672 points of which 3714 are ignored due to dmin).












	
> If you cannot get reasonable results from your data set it would be better
> if you send us the data and region information so that we can find
> out where the problem is. You can try to run s.surf.tps on your
> old data set or any other data you have to see whether your installation 
> of program works OK.

	I can send you any information you need, but as yet I can't seem
	to get any useful output from s.surf.tps and friends :-(

	Martin